This invention relates to antenatal screening for risk of Down's Syndrome in a foetus.
Risk of Down's syndrome in a foetus is known to increase with the age of the mother and it is this fact which forms the basis for selection of mothers for further investigation. Further testing involves sampling of the amniotic fluid by amniocentesis, a procedure which is not completely free from risk to the mother or foetus, induction of miscarriage being a recognised hazard.
The amniotic fluid test for Down's syndrome (the recognition of an extra chromosome 21 in foetal cells) is diagnostic.
There is a need for a screening method which will identify pregnancies most at risk so as to justify amniocentesis with its attendant risks.
An object of the present invention is to provide an improved screening procedure.